In a large saucepan, bring broth and water to a boil; stir in 2 tbsp. thyme, 2 tsp. sage, wild rice and mushrooms. Return to a boil; reduce heat and simmer, covered, until most of wild rice kernels open (45-55 min.). In a large skillet, melt butter; stir in celery and onions. Sauté until tender (about 10 min.). Stir celery mixture, croutons, parsley, seasonings, remaining thyme and sage into wild rice and mushrooms. Spoon into a greased 3 qt. casserole. Bake, covered, in a preheated 325° oven until heated through (40-45 min.).